What is the fourth trimester?

The fourth trimester is a subject that has been gaining increased attention in recent years. This stage of a baby's life is recognised as being a significant time in their development. Here's what you need to know about exactly what the fourth trimester is, and why it is such an important stage for your baby.

What is the fourth trimester?

As you will already know, the various stages of pregnancy are known as the first, second and third trimester. These trimesters refer to stages of your baby's development in the womb. The fourth trimester refers to the three months following your baby's birth.

Why is this stage called the fourth trimester?

The first few months of a baby's life are referred to as the fourth trimester, as this is a time of crucial changes in your baby's life. Just as significant changes happened to your baby during each trimester in the womb, their first three months outside of the womb are also a time of incredible changes. This stage is also a time of adaptation for new parents too. During this period, you will adjust to no longer being pregnant and start to settle into life with your new addition to the family.

Why is the fourth trimester so significant?

After the comfort and warmth of being in the womb, life in the outside world is a shock to a newborn. All those months safely tucked away are suddenly replaced with being exposed to the air and loud noises, as well as no longer being in constant contact with you.

A steep learning curve takes place for babies during the fourth trimester. Human babies are entirely reliant on their parents for food and comfort and are unable to move around of their own accord. This is in sharp contrast to other young mammals who can walk around independently within moments of birth. Humans take time to develop the skills and capability needed to be independent, and the fourth trimester is the very start of this process.

How does a baby develop during the fourth trimester?

During the fourth trimester, your baby will be adapting to life outside of the womb and growing used to their new environment. Over their first three months your baby's senses will continue to develop. A newborn baby will be able to see, but their vision will be blurry and will take a couple of months to develop fully.

Your baby will have muffled hearing at birth but will be able to recognise the sound of your voice after hearing it when they were in the womb. As they get a little older, your baby will start to turn to look at you when they hear you speaking.

With all these changes happening during this time of adjustment, your baby will spend a lot of their time asleep. The reason that babies sleep so much is not simply because they are physically growing; a baby's nervous system continues to develop after birth, along with neural pathways. Sleep provides young babies with the opportunity for their brain to process all the new sights, sounds and smells they have experienced throughout the day.

As your baby grows accustomed to life outside the womb, you will probably notice they are less bothered by things that upset them when they were first born. They may become less disturbed and jumpy at noises, and able to sleep through noises that would have upset them previously.

Your baby will become more aware of their surroundings and the people around them as they progress through their fourth trimester. They will become more interested in interacting with people, by watching people intently and responding to attention with a smile.

How do I support my baby during their fourth trimester?

The fourth trimester is a very special time, as your baby is rapidly developing, you are adjusting to life together, and developing the bond between you as a family.

Many new parents are advised by older relatives to let their baby self-soothe, so they don't become spoilt. In truth, it is impossible to spoil a baby by responding to its cues. A baby that feels secure and comforted is likely to cry less and to be calmer.

Your baby's stomach is around the size of a cherry at birth, which means that they will need to be fed little and often. Feeding on demand is the best way to give your baby just the right amount of milk.

Using a sling and having plenty of skin to skin time are great ways to calm and settle your baby. This is because the sound of your heartbeat and familiar smell will help soothe them.

Talking to your baby and singing to them will help to stimulate their senses, as well as strengthening the connection between you.

The information on this website is for general information and it is not intended as, nor should it be considered as a substitute for seeing your own GP, midwife or healthcare professional. You are advised to seek professional medical advice if you have any concerns or suspect you have a medical problem.